Electronic equipment cabinet

ABSTRACT

There is provided an electronic equipment cabinet including a cabinet carcass ( 15 ) mounting fan cooled equipment ( 16 ) venting to the cabinet rear. A hinged front closure assembly ( 11 ) includes a frame ( 14 ) and an outer filter and perforated metal screen assembly on the outer face of the frame, and a lower condensation trap ( 20 ). The frame  14  supports an evaporator assembly ( 11 ) connected to a remote compressor/condenser assembly (not shown). The evaporator assembly includes a combined dew point sensor and thermostat ( 13 ). A non-woven filter web ( 19 ) acts a micro-droplet catcher on the inner face of the door assembly.

FIELD OF THE INVENTION

This invention relates to an electronic equipment cabinet. Thisinvention has particular application to an electronic equipment cabinetfor controlling the temperature environment for electronic equipmentrack mounted within the cabinet, and for illustrative purposes theinvention will be described with reference to this application. Howeverwe envisage that this invention may find use in other applications suchas environment conditioning of cabinets and enclosures generally.

BACKGROUND OF THE INVENTION

The reference to any prior art in this specification is not, and shouldnot be taken as, an acknowledgement or any form of suggestion that thereferenced prior art forms part of the common general knowledge inAustralia or elsewhere.

Many data processing centres are configured around microprocessor-based,standard rack-mounted equipment adapted to be mounted in metal rackswithin ventilated, generally metal cabinet enclosures. A typical dataprocessing centre will have ranks of cabinets. Microprocessor basedequipment and the associated hubs, hard drive and other NAS devices aregenerally configured to be air cooled, with integral fans and agenerally front to rear air flow path through the equipment. Theequipment is thereby rendered independent of the types of coolingsystems required for mini- and mainframe computer hardware. Thisindependence from connectable cooling means that control of thecondition of the air within the building space environment containing adata processing centre is used to provide overall temperature control.

The dependence on control of the condition of the environmental air tocontrol the operating temperature has several disadvantages. The systemsare not readily scalable in that the plant must be engineered to dealwith the worst case peak thermal load and temperature differential.There is a basic cost for idling capacity below the peak load. Moreimportantly, environmental air control imposes planning geometry on thespace to avoid hot spots. The corollary is that there is a risk ofcertain cabinets getting less than optimal cooling air.

A proprietary system of Sun Microsystems Inc provides more efficientrack cooling than standard datacenter cooling systems to significantlyreduce energy consumption and increase effective compute density by upto 70 percent over in-row, environmental cooling options. The systemcomprises a cold water or refrigerant chilled rear door to the SUN BLADE6048 modular system. It is a passive design that does not requireadditional fans or electrical power to function. The cooling systemremoves heat from the exhaust air blade unit exhaust air and requiresminimal data centre footprint. Up to 35 kW of cooling capacity per dooris available, a considerable increase over traditional raised floorcooling. The system is configured with humidity sensor-mediatedthermostatic control to ensure that air exiting the system is not cooledbelow 2° C. above the dew point.

This system is specifically tailored to its proprietary Sun Microsystemsenvironment. There is a need for a more generalized solution. It isespecially not suited to installations of CISCO® switches, where lack ofcontrol of the incoming air may cause a DPS shutdown.

SUMMARY OF THE INVENTION

In one aspect the present invention resides broadly in an electronicequipment cabinet including:

-   -   a cabinet body having a ventilated rear wall and a front opening        providing access to rack mounted equipment within the cabinet of        the type having an integral cooling fan venting through said        ventilated rear wall;    -   a ventilated front closure assembly adapted to selectively close        said front opening and including an air-to-coolant heat exchange        panel and an air filtration medium adjacent the heat exchange        panel on the equipment side thereof; and forming a continuous        air flow path from outside of the cabinet body through the        ventilated front closure, said rack mounted equipment and said        ventilated rear wall; and        -   heat pump means connected to said heat exchange panel and            operable to thermally condition air passing through said air            flow path.

In most cases, the heat exchange panel and heat pump means will beselected to condition air for cooling purposes, and for the purposes ofdescription of the invention this function will be emphasized. However,it must be envisaged that under certain circumstances it may bedesirable to condition the air to heat equipment to an optimum operatingtemperature. This heating may be part of a controlled cycle includingcooling functions, wherein the transitions between heating and coolingare managed by operation of a reverse-cycle heat pump or desiccated heatpumps driving separate heat exchange evaporator and condenser units inthe heat exchange panel.

The air filtration medium may be selected from woven or non-wovenmaterials. It has been surprisingly determined that, even with controlof operation of a panel by the use of a humidity sensor, highlylocalized conditions can promote the formation of condensation. In theusual usage a filter medium would be located on the outside of the panelto prevent dust from entering the heat exchanger panel. However, thelocation of the air filter medium adjacent to the heat exchanger panelon the inside not only prevents dust circulation but prevents occasionalinstances of condensation from being entrained in the airflow. The airfiltration medium may comprise an air filtration web mounted on a framesupported on the inner surface of the ventilated front closure.Alternatively the air filtration medium may comprise an air filtrationweb trapped by a mesh faced frame supported on the inner surface of theventilated front closure

In the event of a failure of environmental air conditioning resulting ina significant increase in humidity and temperature, or in the event ofan environmental increase in humidity, condensation may form on thepanel. This may be dispersed by diffusion through the air filter mediumor other media facing the panel. There may be provided a condensationcollection tray at the foot of the panel. The tray may be associatedwith wicking means do dissipate any collected water as vapour undernon-condensing conditions.

In preferred embodiments of the present invention there is provided aircurtain means adapted to pass air vertically downward across the face ofthe heat exchanger panel. For example there may be provided a header fanassembly comprising housing for a barrel fan impeller and having adirectional slot directing an air curtain across the face of the heatexchanger panel. It has been found that the use of an air curtain inthis manner disturbs the air ahead of the panel and adds somecondensation control. This is a surprising result.

The equipment may be supported in the cabinet on support means which maycomprise a standard or proprietary racking arrangement for one or moreunits of equipment. In certain embodiments of the present invention, thesupport means is a racking arrangement mounted within a metal equipmentcabinet. Such cabinets are usually configured for airflow, having a netflow path from the front and/or floor and venting to the back and/ortop.

The heat exchange panel may comprise a front closure for a cabinethousing the support means and the equipment supported thereby. The frontclosure may include a frame member defining a front aperture into whichis mounted the heat exchange panel. The front closure may be removablysecured to the cabinet. Alternatively the front panel may be hinged tothe cabinet in the form of a door. Equipment may be stacked verticallyin 19″ (480 mm) standard equipment racks in standard metal cabinets,wherein the front closure may replace the standard cabinet front door.

Cabinet closure-forming heat exchange panels have a particular advantagein that the cooling air inlet vents of the rack-mounted equipment can bemaintained in relatively close proximity to the heat exchanger.Accordingly the cooling air passing into the equipment has for the mostpart passed through only that portion of the heat exchanger adjacent theequipment. The heat exchanger may include separately cooled zonescorresponding to the position of the respective equipment items.However, where the heat exchanger is monolithic, the localization of airflow means that heat transfer occurs most in the region of theequipment. The heat is then distributed by the coolant and/or byconduction throughout the heat exchanger body depending on the coolingmethod employed. The effect is one of self regulation where the coolingeffort supplied by the heat exchanger is automatically proportional tothe population of equipment items in the cabinet.

The heat exchange panel may be associated with other air conditioningdevices such as upstream particulate filters including HEPA filters,adsorbents, and the like. For example, in cabinet closure types of heatexchanger panels, the frame may include a mount for a filter assembly,such as a slide-in mount for a filter assembly having a bordering frame.

The heat exchange panel may be selected from any suitable heat exchangemeans including but not limited to solid state cooling devices, Carnotcycle heat pump or phase change regenerative cooling or Siemens cycleheat pump. For example the heat exchange panel may comprise theevaporator unit or reverse cycle evaporator/condenser unit of aconventional refrigeration plant. The heat exchanged by the heatexchanger panel may be disposed of the local environment. However, it ispreferred that the heat be conveyed for remote disposal or recovery. Forexample the radiator of the heat pump may be co-located with the heatexchanger and coupled to a heat disposal exchanger cooled by air orliquid coolant. Where conventional refrigeration plant is used, the heatexchanger may be connected in circuit with a remote compressor/condenserassembly.

Where remote refrigeration plant is used, this may be of the single heador multi-head design. For example, there may be used a remotecompressor/condenser unit that is capable of operating two or more heatexchange panels such as the abovementioned cabinet door units.

The heat exchange panel may be associated directly or indirectly withcontrol means for monitoring and controlling the heat pump activity ofthe panel. For example, the heat exchange panel may include thermallyconductive parts including a reference part having a transducer or othersensor mounted thereon. The sensor may be used to control a TX valve orother suitable scaling device selected according to the type of heatpump and the direction of the cycle at the time. Cabinet enclosures orother housings may include sensors to detect any one of both oftemperature and air flow. In addition or in the alternative, theoperating temperature may be sensed and appropriate control signalsgenerated by monitoring means associated with the equipment per se.

In a further aspect the present invention resides broadly in a method oftemperature-controlling electronic equipment of the type having a nativethermal regulating air flow, including supporting the equipment relativeto a heat exchange panel having a heat exchanging air flow paththerethrough, and operating heat pump means connected to said heatexchange panel to thermally condition air passing through said heatexchanging air flow path, whereby temperature regulating air is drawn bysaid native thermal regulating air flow from said heat exchanging airflow path.

Apparatus in accordance with the foregoing may be powered by energyefficient means such as direct solar to LV compressor technology or maybe integrated into the grid by conventional solar-to-invertertechnology.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the followingnon-limiting embodiment of the invention as illustrated in the drawingsand wherein:

FIG. 1 is an isometric view of apparatus in accordance with the presentinvention;

FIG. 5 is a plot of air flow through the apparatus of FIG. 1;

FIG. 6 is; a plot of dew point inside the equipment cabinet of the airflow through the apparatus of FIG. 1

FIG. 7 is a plot of air temperature inside the equipment cabinet of theair flow through the apparatus of FIG. 1;

FIG. 8 is a plot of high temperature test air temperature passing intothe equipment cabinet of the apparatus of FIG. 1;

FIG. 9 is a plot of high temperature test air temperature having passedinto the equipment cabinet of the apparatus of FIG. 1; and

FIG. 10 is a plot of the evaporator core temperature during the hightemperature test of FIGS. 8 and 9.

In FIG. 1 there is provided an electronic equipment cabinet including acabinet carcass 15 mounting rack mounted computer equipment 16 in aconventional manner. The equipment is fan cooled and exhaust air 17exits at the rear of the cabinet 15. A front closure assembly 11 ishinged by lift-off hinges 12 and is shown in an open position forservicing the front closure 11 and/or the racked equipment 16. FIGS. 2-4illustrate the exploded components of the front closure 11.

The front closure assembly 11 is built up on a door frame 14 issupported on the cabinet 15 by the hinges 12. An outer filter and screenassembly 16 is supported on the outer face of the door frame andincludes a perforated metal protective screen. The lower edge of thedoor frame 14 is provided with a condensation trap 20.

The door frame 14 supports on its inner face an evaporator assembly 11connected to a remote, approximately 2 kW heat pump capacity,compressor/condenser assembly (not shown). The evaporator assemblyincludes regulation elements including a combined dew point sensor andthermostat 13. The suction and delivery lines 18 are connected byflexible lines to enable operation of the door. A non-woven filter web19 acts a micro-droplet catcher on the inner face of the door assembly.

In use, the equipment 16 rack mounted in the cabinet 15 operates andgenerates heat. Internal sensors switch internal fans drawing coolingair from front vents and exhausting air through rear vents. The fans arethermally switched to save energy.

FIG. 5 illustrates a data-logged period of time from 2300 hrs to 0541hrs of an installed stack of equipment having 6 fan modes in total.Environmental and peak processing load variables results in a flux ofair from front to back of the cabinet. When all units are at maximumcooling, the maximum velocity V_(max) measured through the plane of thedoor assembly is approximately 23 m·min⁻¹. The plot of FIG. 5 showsinteger air flows being highest from 2200 to 0200 and lowest from 0200to the end of the log, forming in essence two broad cooling states.

The evaporator assembly 11 is operated under the primary control of thethermostat 13 and secondary control of the dew point sensor. FIGS. 6 and10 indicate an initial state of fluctuating dew point and temperatureunder load from start-up at 2300 to 0000, as the oscillating feedbackloop of temperature and dew point operate the panel. After 0000, anapproximate steady state operating temperature of the evaporator panelper se is reached (FIG. 10).

The dew point of air on the equipment side of the evaporator assembly 11plots an average curve from about 23.8° C. at 0000 to a broad peak ofabout 25.25 centred about 0300 (FIG. 6). This is a measure of theabsolute moisture content of the environmental air. Simultaneously, thetemperature plot curve of FIG. 7, measuring the exhaust air temperaturefrom the cabinet, slowly increases from 30° C. at 2300 to a broad peakof about 31.1° C. between 0100 and 0200, followed by a steep declinecorresponding exactly to the switching off of ⅔ of the cooling fans at0200. The minimum temperature of 28.8° C. is safely above the dew pointat the same time, as is the dew point at each relevant point of the airtemperature plot, despite there being no direct coupling of the dewpoint (dependent only on the environment) and temperature (dependent onboth control feedback and equipment thermal load) plots.

In FIGS. 8 and 9, there is illustrated the results of a thermal stresstest where hot air is applied to the exterior front of the evaporatorassembly. FIG. 8 is the plot of temperature against time measured by aprobe supported adjacent to but thermally insulated from the evaporatorassembly. The plot shows that the air temperature increased steeply fromstart up at just after 2300 to 60° C. and then increased more or lesssmoothly to a plateau of about 68.3° C. At the same time, the exit airtemperature plot of FIG. 9 shows two plateaus, a first between 0000 and0200 of about 34.5° C. and a second between 0200 and 0500 of about 33.5°C. These plateaux correspond exactly to the peak and off-peak processingload cooling requirements. The comparison indicates that apparatus inaccordance with the present invention can cope with environmental shocksuch as long term environmental air conditioning failure.

It will of course be realised that while the above has been given by wayof illustrative example of this invention, all such and othermodifications and variations thereto as would be apparent to personsskilled in the art are deemed to fall within the broad scope and ambitof this invention as is set forth in the claims appended hereto.

1. An electronic equipment cabinet including: a cabinet body having aventilated rear wall and a front opening providing access to rackmounted equipment within the cabinet of the type having an integralcooling fan venting through said ventilated rear wall; a ventilatedfront closure assembly adapted to selectively close said front openingand including an air-to-coolant heat exchange panel and an airfiltration medium adjacent the heat exchange panel on the equipment sidethereof; and forming a continuous air flow path from outside of thecabinet body through the ventilated front closure, said rack mountedequipment and said ventilated rear wall; and heat pump means connectedto said heat exchange panel and operable to thermally condition airpassing through said air flow path.
 2. Air conditioning apparatusaccording to claim 1, wherein the heat exchange panel and heat pumpmeans are selected to condition air for cooling purposes.
 3. Airconditioning apparatus according to claim 1, wherein the air filtrationmedium is selected from woven or non-woven materials.
 4. Airconditioning apparatus according to claim 1, wherein there is provided acondensation collection tray at the foot of the panel.
 5. Airconditioning apparatus according to claim 1, wherein there is providedair curtain means adapted to pass air vertically downward across theface of the heat exchanger panel.
 6. Air conditioning apparatusaccording to claim 1, wherein the air curtain means is provided by aheader fan assembly comprising housing for a barrel fan impeller andhaving a directional slot directing an air curtain across the face ofthe heat exchanger panel.
 7. Air conditioning apparatus according toclaim 1, wherein said support means includes a racking arrangementmounted within an equipment cabinet.
 8. Air conditioning apparatusaccording to claim 1, wherein the front closure assembly includes aframe member defining a front aperture into which is mounted the heatexchange panel.
 9. Air conditioning apparatus according to claim 1,wherein the front closure assembly is removably secured to the cabinet.10. Air conditioning apparatus according to claim 1, wherein the frontclosure is hinged to the cabinet in the form of a door.
 11. Airconditioning apparatus according to claim 10, wherein the equipment isstacked vertically in 19″ (480 mm) standard equipment racks in standardmetal cabinets, wherein the front closure replaces the standard cabinetfront door.
 12. Air conditioning apparatus according to claim 1, whereinthe heat exchange panel includes separately cooled zones correspondingto the position of respective equipment items.
 13. Air conditioningapparatus according to claim 1, wherein the heat exchange panel isassociated with one or more of filters including HEPA filters,adsorbents, and the like.
 14. Air conditioning apparatus according toclaim 1, wherein the heat exchange panel and heat pump in assembly isselected from one or more of solid state cooling devices, Carnot cycleheat pump, phase change regenerative cooling and Siemens cycle heatpump.
 15. Air conditioning apparatus according to claim 14, wherein theheat exchange panel comprises the evaporator unit or reverse cycleevaporator/condenser unit of a conventional refrigeration plant.
 16. Airconditioning apparatus according to claim 15, wherein the heat exchangedby the heat exchanger panel is conveyed for remote disposal or recovery.17. Air conditioning apparatus according to claim 15, wherein theradiator of the heat pump may be co-located with the heat exchange paneland coupled to a heat disposal exchanger cooled by air or liquidcoolant.
 18. Air conditioning apparatus according to claim 16, whereinconventional refrigeration plant is used, and the heat exchange panel isconnected in circuit with a remote compressor/condenser assembly. 19.Air conditioning apparatus according to claim 15, wherein said heat pumpcomprises remote refrigeration plant of single head or multi-head designto drive a single or multiple said heat exchange panels respectively.20. Air conditioning apparatus according to claim 15, wherein the heatexchange panel is associated with control means for monitoring andcontrolling the heat pump.
 21. A method of temperature-controllingelectronic equipment of the type having a native thermal regulating airflow, including supporting the equipment relative to a heat exchangepanel having a heat exchanging air flow path therethrough, and operatingheat pump means connected to said heat exchange panel to thermallycondition air passing through said heat exchanging air flow path,whereby temperature regulating air is drawn by said native thermalregulating air flow from said heat exchanging air flow path.